The present invention relates to a damping device for use in an auto-close mechanism of a sliding rail assembly for drawer, sliding door or any other furniture and more particularly, to a flow damper for drawer, which is comprised of two hydraulic cylinders arranged in parallel in reversed directions, thereby saving much installation space and providing a relatively longer buffer stroke.                Various hydraulic and pneumatic dampers are known and intensively used in drawers, sliding doors and many other furniture. FIG. 1 shows an extended status of a conventional design of flow damper 3 for this purpose. This design of conventional flow damper has drawbacks as follows:        1. This design of flow damper has a limited buffer stroke. When a relatively longer buffer stroke is necessary, the length of the flow cylinder and the piston rod must be relatively increased. However, extending the size of the flow damper will require a relatively greater installation space in the furniture (for example, the sliding rail assembly of the drawer). Therefore, the application of this design of flow damper is limited.        2. If the furniture in which the flow damper is used requires a relatively greater damping resistance, the size of the flow damper must be relatively increased to enhance the damping.        Therefore, there is a demand for a flow damper that eliminates the aforesaid problem.        
The present invention has been accomplished under the circumstances in view. It is one object of the present invention to provide a flow damper, which provides a relatively longer buffer stroke and requires less installation space.
It is another object of the present invention to provide a flow damper, which allows the user to arrange the two flow cylinders in parallel in a same direction or reversed directions to fit different application requirements.
To achieve these and other objects of the present invention, the flow damper comprises a first flow cylinder and a second flow cylinder. The first and second flow cylinders each have a cylinder body filled with a flow substance, a piston accommodated and axially slidable in the cylinder body, and a piston rod connected to the piston and extending out of one end of the cylinder body and movably forwards/backwards with the piston relative to the cylinder body. Further, the cylinder body of the first flow cylinder has at least one coupling groove disposed at one lateral side thereof; the cylinder body of the second flow cylinder has at least one coupling block disposed at one lateral side thereof and respectively connectable to the at least one coupling groove of the first flow cylinder to secure the first flow cylinder and the second flow cylinder in parallel in one of a first condition where the piston rods of the first and second flow cylinders extend in the same direction and a second condition where the piston rods of the first and second flow cylinders extend in reversed directions.